Hi David, thanks for looking at this!
> -----Original Message----- > From: David Holmes [mailto:david.hol...@oracle.com] > Sent: Donnerstag, 12. November 2015 08:35 > To: Lindenmaier, Goetz; hotspot-runtime-...@openjdk.java.net; > serviceability-dev > Subject: Re: RFR(M): 8141529: Fix handling of _JAVA_SR_SIGNUM > > Hi Goetz, > > Adding in serviceability-dev > > On 9/11/2015 6:22 PM, Lindenmaier, Goetz wrote: > > Hi, > > > > The environment variable _JAVA_SR_SIGNUM can be set to a signal > number > > do be used by the JVM's suspend/resume mechanism. > > > > If set, a signal handler is installed and the current signal handler is > > saved to > an array. > > On linux, this array had size MAXSIGNUM=32, and _JAVA_SR_SIGNUM was > allowed > > to range up to _NSIG=65. This could cause memory corruption. > > > > Further, in jsig.c, an unsinged int is used to set a bit for signals. This > > also > > is too small, as only 32 signals can be supported. Further, the signals are > mapped > > wrong to these bits. '0' is not a valid signal, but '32' was. 1<<32 > > happens to > map to > > zero, so the signal could be stored, but this probably was not intended that > way. > > > > This change increases MAXSIGNUM to 65 on linux, and to 64 on aix. It > introduces > > proper checking of the signal read from the env var, and issues a warning if > it > > does not use the signal set. It adapts the data types in jisig.c properly. > > > > Please review this change. I please need a sponsor. > > http://cr.openjdk.java.net/~goetz/webrevs/8141529-NSIG/webrev.00 > > This all sounds very good to me. (I must find out why Solaris is not > involved here :) ). The mechanism is not implemented there. Why, I don't know. > On Linux you didn't add the bounds check to os::Linux::set_our_sigflags. It came with 8140482 http://hg.openjdk.java.net/jdk9/hs-rt/hotspot/rev/cd86b5699825 > I'm also wondering about documenting where we are determining the > maximum from? Is it simply _NSIG on some/all distributions? And I see > _NSIG is supposed to be the biggest signal number + one. Also linux > defines NSIG = _NSIG so which should we be using? I checked a row of linux distributions and Versions and always found NSIG=65. Also, as we compile NSIG into the code, we can not react on a difference between systems. So I guess that's fine. As NSIG = _NSIG, I don't really care which we use. I chose _NSIG because it was used before. On the other platforms I only found NSIG in the header files. Best regards, Goetz > > Thanks, > David > > > Best regards, > > Goetz. > >
